Steroid hormone nuclear receptors represent a subset of the nuclear hormone receptor superfamily. So named according to the cognate ligand which complexes with the receptor in its native state, the steroid hormone nuclear receptors include the glucocorticoid receptor (GR), the androgen receptor (AR), the mineralocorticoid receptor (MR), the estrogen receptor (ER), and the progesterone receptor (PR). MR is expressed in epithelial tissues, heart, kidneys, brain, vascular tissues and bone. Aldosterone is the endogenous ligand of MR and is primarily synthesized in the adrenal glands, heart, brain and blood vessels. Several detrimental effects are attributable to aldosterone, for example: sodium/water retention, renal fibrosis, vascular inflammation, vascular fibrosis, endothelial dysfunction, coronary inflammation, decrease in coronary blood flow, ventricular arrhythmias, myocardial fibrosis, ventricular hypertrophy and direct damage to cardiovascular systems, primarily the heart, vasculature and kidneys. Aldosterone action on all target organs is through activation of the MR receptor. GR is expressed in almost all tissues and organ systems and is crucial for the integrity of the function of the central nervous system and the maintenance of cardiovascular, metabolic, and immune homeostasis.